Proof of existence for digital files
Prove it existed.Without revealing it.
Some files matter later. A contract draft, a design, a manuscript, a photograph, a set of research notes. Private Notary creates cryptographic evidence that one exact file already existed — and records that evidence permanently on the public Solana blockchain.
The file itself stays on your device. We never receive it, so we can never read it, lose it or leak it.
…or drop it here. Any file type, any size your browser can read.
- €4.50 once
- No account
- File never uploaded
- Verification always free
“We don’t ask you to trust us. We give you a proof you can verify without us.”
Your proof does not depend on this company continuing to exist. It can be checked against the public blockchain record by anyone, with any compatible tool, using only your original file and your proof package.
- Price
- €4.50 per proof, one-timeTaxes included where applicable
- Verification
- Free, forever, no account
- Recorded on
- Solana, public blockchain
- We receive
- A cryptographic commitment only — never your file, its hash or your private salt
How it works
Four steps. Nothing to install, nothing to publish, nothing to trust.
Select your file
Your browser reads the file and derives a cryptographic fingerprint on your device. The file is never uploaded.
Create the proof
After payment, the evidence — and only the evidence — is recorded on the public Solana blockchain.
Keep your proof
Download the proof package and the human-readable record, and store them beside the exact original file.
Verify when it matters
Years later, the free verifier rebuilds the proof from your file and re-checks the public blockchain record.
What the evidence means
What a verified proof shows
- That one exact file — byte for byte identical to the one you hold — already existed no later than the time recorded by the blockchain.
- That the record has been on a public, independent blockchain since that moment, and cannot be back-dated by us or by you.
- That any change to the file, however small, will fail verification.
What it does not show
- Who wrote or owns the file, or who holds any rights in it.
- Whether the contents of the document are true, accurate or complete.
- Private Notary is not a public notary, statutory notarisation, electronic signature, qualified timestamp or legal certification, and does not guarantee how any court or authority will weigh the evidence.
The Terms of Service define these boundaries and are authoritative.
Who uses it
For anyone who may one day have to show that a file already existed.
Lawyers and advisers
Draft agreements, disclosures, correspondence and evidence files.
Companies and directors
Board material, internal records, decisions and specifications.
Architects and engineers
Plans, models, calculations and revisions.
Photographers and creators
Originals, masters and unpublished work.
Authors and researchers
Manuscripts, datasets, lab notes and findings.
Inventors
Disclosures and development records kept confidential before filing.
Privacy by architecture, not by promise
We designed the service so that we could not betray your confidence even if we wanted to.
Your file, its fingerprint and — in Private mode — the random salt that protects it never leave your browser. What reaches us is a single commitment value from which the document cannot be reconstructed or guessed.
Nothing in the blockchain record reveals the file, its name, its type or its size. There is no account, no document storage and no upload.
Because your proof package lives with you, keeping it safe is your responsibility. If you lose the exact original file or the proof package, the proof can no longer be verified.
Record a file today.
€4.50, one payment, no account. Verification stays free — including for proofs you already hold.
Already hold a .pnproof.json file? Verification never expires and never costs anything.